Sealing means for a regenerative heat exchanger

ABSTRACT

Sealing means for a heat exchanger having a rotary matrix type regenerator which is disposed across conduit means for high temperature fluid and a second conduit means for low temperature fluid, said sealing means including a pair of parallel annular flexible plates which are connected together at their outer peripheries through a ring member, one of said flexible plate being connected with an opening of one conduit means, the other of said conduit means having a sealing member at its inner periphery, said sealing member being forced in sealing contact with the regenerator by the pressure difference between the inside and outside of the conduit means.

[ Nov. 20, 1973 SEALING MEANS FOR A REGENERATIVE HEAT EXCHANGER [75] Inventor: Yasuo Kondo, Anjo, Japan [73] Assignee: Nippondenso Co., Ltd., Aichi-ken,

Japan [22] Filed: Dec. 6, 1971 [21] Appl. No.2 205,010

[30] Foreign Application Priority Data 3,368,611 2/1968 Bracken, Jr et al. 165/9 X 3,401,740 9/1968 Trudeau 16519 X FOREIGN PATENTS OR APPLICATIONS 876,194 8/1961 Great Britain 277/88 Primary ExaminerAlbert W. Davis, Jr. Attorney-Cushman, Darby & Cushman [57 ABSTRACT Sealing means for a heat exchanger having a rotary matrix type regenerator which is disposed across conduit means for high temperature fluid and a second conduit means for low temperature fluid, said sealing means including a pair of parallel annular flexible plates which are connected together at their outer peripheries through a ring member, one of said flexible plate being connected with an opening of one conduit means, the other of said conduit means having a sealing member at its inner periphery, said sealing member being forced in sealing contact with the regenerator by the pressure difference between the inside and outside of the conduit means.

2 Claims, 4 Drawing Figures PATENTEUunvzn I973 SHEET 2 BF 2 INVENTOR ATTORNEYS SEALING MEANS FOR A REGENERATWE HEAT EXCHANGER The present invention relates to sealing means and more particularly to gas sealing means for a heat exchanger having a rotary matrix type regenerator.

Such a heat exchanger that has a rotary matrix type regenerator is conventionally used in a gas turbine engine. A heat exchanger of this type usually includes a gas sealing means comprising a sealing member in the form of a D-shaped ring like element, a flexible bellows of a similar shape and a flange, said sealing means being adapted to be put into sealing contact with an end surface of the heat accumulator. High pressure air is passed through the interior of the sealing member to displace the member toward the co-operating surface of the rotary matrix type regenerator so as to put the member into sealing contact with the surface of the regenerator. Thus, the sealing member effectively separates conduits for passing high temperature and low pressure combustion gas from conduits for passing low temperature and high pressure fresh air. The flexible bellows is intended to allow the sealing member to have a stable sealing contact with the co-operating surface of the rotary matrix type regenerator irrespective of the circumstances which may be encountered during operation. For example, the gap between the surface of the regenerator and the co-operating surface of the sealing member must be less than 0.025 mm. Otherwise, an increased air leakage will cause an excessive decrease in heat exchange performance resulting in a decrease in the ultimate engine performance. For this reason, in order to solve the sealing problem, many proposals have been made, however, most of them have not been satisfactory since they are complex in structure and expensive to manufacture. The aforementioned type of sealing means having a flexible bellows is relatively simple in structure. However, it still have problems in the durability of the bellows and in manufacturing and assembling the sealing means. Further, this type of sealing means is also disadvantageous in that it occupies a considerable space. Moreover, this type of sealing means does not provide a satisfactory sealing performance due to an uneven rigidity of the flexible bellows.

The present invention has an object to provide a sealing means for a regenerator type heat exchanger which is free from the above problems and easy and less expensive to manufacture.

According to the present invention, in a heat exchanger having a rotary matrix type regenerator and a stationary sealing member which is disposed in confronting relation with the regenerator, two flexible ring like plates are arranged between the sealing member and an open end of a conduit for passing fluid toward said regenerator. One of the flexible plates is secured at the inner periphery to the open end of said conduit while the other of the flexible plate is secured at the inner periphery to the sealing member. These flexible plates are connected at their outer periphery to a common ring like holding member so that they extend in parallel relation with each other. This arrangement is effective to attain an increased sealing effect and a prolonged life. Further, the sealing means is easy and less expensive to manufacture.

The above and other objects and features of the present invention will become apparent from the following descriptions of a preferred embodiment taking reference to the accompanying drawings, in which;

P16. 1 is a fragmentary sectional view of a sealing means for a regenerator type heat exchanger embodying the present invention;

FIG. 2 is a perspective view of the rotary matrix type regenerator with a part being cut away to show the interior of the regenerator;

FIG. 3 is a perspective view of the details of the sealing structure and the rotary matrix portion; and,

P16. 4 is a fragmentary sectional view showing the details of the sealing structure.

Referring to the drawings, particularly to FIGS. 1 and 2, the reference numeral 1 shows a disc shaped rotary matrix type regenerator including a plurality of axial passages 20 and 22, which is made for example of ceramic material. A solid ring 19 of ceramic material is secured by an adhesive to the outer periphery of the matrix. The solid ring 19 has secured thereto a metallic drive ring 3 having sprocket teeth 3a. The reference numeral 5 shows an air conduit for passing compressed fresh air and 4 a gas conduit for passing combustion gas of the gas turbine engine. The rotary matrix type regenerator 1 is so arranged that it rotates across the conduits 4 and 5. The reference numeral 9 shows a rotatable shaft for supporting the heat accumulator l, and 10 a shaft which is driven by the gas turbine engine and having a sprocket 7 secured to one end thereof. The reference numeral 6 shows a chain passing around the sprocket '7 and the sprocket teeth 3a formed around the driving ring 3 so as to transmit the driving force from the shaft 10 to the accumulator 1. The regenerator 1 is rotated at a speed of about 20 rpm.

The sealing structure between the rotary matrix type regenerator ll and the conduits 4 and 5 will now be described. Referring first to the sealing structure relating to the air conduit 5 taking reference to FIGS. 3 and 4), the reference numeral 2 generally shows a gas sealing structure comprising a stationary sealing member 12 having a surface 12a which is adapted to be placed in a confronting relation with respect to the adjacent surface of the rotary matrix type regenerator 1 with a gap less than 0.025 mm. The sealing member 12 has a projection 12b to which a flexible ring like plate 15 is secured at its inner periphery by suitable means such as welding. A similar ring like plate 14 is secured at its inner periphery to one surface 130 of a flange 13 by suitable means such as welding. The flange 13 is secured to the open end 50 of the air conduit 5 by bolts 1 1 screwed into threaded holes 21 formed in the flange 13. The spacing 18 between the flexible plates 14 and 15 are adjusted to a predetermined value. The flexible plates 14! and 15 are connected together with the intervention of a rigid holdingring 16 at their outer periphery by suitable means such as welding. Outside the flexible plates 14 and 15, there are also disposed reinforcing plates 17 welded to the flexible plates 14 and 15. The ring 16 has a thickness equal to the spacing 18 so that the flexible plates 14 and 15 extend parallel with each other. in the sealing structure 2 constructed as described above, the sealing member 12, the flange 13 and the holding ring 16 are of rigid material. The flexible plates 14 and 15 can deflect under the air pressure in the air conduit 5 to cause the surface of the sealing member 12 to move toward the adjacent surface of the regenerator 1 so as to accommodate any change in the spacing between the surface of the rotary matrix regenerator 1 and the open end So of the air conduit supporting the flange 13. Each of the reinforcing members 17 is made of a plate member which has a rigidity slightly greater than that of the flexible plates 14 and 15. The sealing member 12, the flexible plates 14 and and the flange 13 may for example be of semicircular ring like shape as shown in FIG. 2. The sealing member 12, the holding ring 16 and the flange 13 may be made of for example stainless steel, and the flexible plates 14 and 15 may be made of flat plates of heat resistant metallic material such as Nimonic by means of stamp forming using a press. The sealing structure between the gas conduit 4 and the rotary matrix regenerator 1 may be similarly constructed except that the sealing member 12, the flexible plates 14 and 15 and the flange 13 are of circular shape, and the sealing member 12 is pressed onto the adjacent end surface of the solid ring 19. Therefore, the detailed description of the sealing structure will be omitted.

The operation of the sealing means in accordance with the present invention will now be described. In this type of heat exchanger, the air in the air conduit 5 is allowed to leak into the gas conduit 4 by being conveyed by the rotation of the rotary matrix type regenerator l in the form of residual air remaining in the passages and 22 of the regenerator 1, through a gap along the sliding surfaces of the sealing member 12 and the rotary matrix type regenerator 1, said gap being provided partially inherent to the structure and partially due to thermal deformation, and through several inperfect welding connections in the sealing structure or possible break produced in the flexible bellows 14 and 15 due to fatigue and the like. The amount of leakage carried by the regenerator 1 is proportional to the rotational speed of the regenerator 1 and neglegibly small. For example, the amount of the leakage is as small as 0.7 percent of the total air flow when the regenerator 1 is rotated at a speed of 20 rpm. The leakage through the sealing means is considered to be caused by the pressure difference between the high pressure side or the air conduit 5 and the low pressure side or the gas conduit 4. According to the present invention, the leakage through the sealing means is prevented in the following manner.

In operation, low temperature and high pressure fresh air are passed through the air conduit 5 and high temperature and low pressure gas or the combustion exhaust gas of the gas turbine engine are passed through the gas conduit 4. As the fresh air and the combustion gas are passed through the rotating matrix type regenerator 1 in the opposite directions, heat energy is given from the combustion gas to the fresh air. in this instance, the pressure of the fresh air is introduced into the space 18 formed between the flexible plates 14 and 15 so as to deflect the plates apart from each other as shown by phantom lines in W6. 4. Thus, the flange 13 and the sealing member 12 are subjected to such forces that tend to urge them away from each other. As the result, the surface 121: of the sealing member 12 is forced into close contact with the adjacent surface of the matrix type regenerator 1. Since the flexible plates 14 and 15 themselves do not have any appreciable elongation, the rigid ring 16 is subjected to a force which draws it toward the flange 13 and the sealing member 12. However, since the ring 16, the flange 13 and the sealing member 12 have sufficient rigidity to retain their semi-circular shapes, no remarkable deformation is produced in the sealing means. Further, the distance between the flange 13 and the sealing member 12, the spacing 18 between the flexible plates 14 and 15, and the dimension of the ring 16 are so determined that the plates 14 and 15 extend in parallel relation along their whole lengths, so that it is possible to substantially reduce bending force on the plates, which has a great effect on the fatigue life of the flexible plates 14 and 15. Thus, according to the arrangement of the present invention, the flexible plates 14 and 15 are mainly subjected to tensile force and serve under the pressure of the compressed fresh air to urge the sealing member 12 onto the surface of the rotary matrix type regenerator 1 so as to provide a stable sealing effect. Further, with respect to the effects of pressure on the welding connections, it should be noted that, at the connection 13a between the flexible plate 14 and the flange 13 and the connection 12b between the flexible plate 15 and the sealing member 12, the plates 14 and 15 are urged toward the flange 13 and the sealing member 12, respectively, so that there is little tendency of separating them apart. At the connection between the flexible plate 14 and the holing ring 16 and the connection 162) between the flexible plate 15 and the holding ring 16, there act concentrated forces to separate the flexible plates 14 and 15 from the ring 16 in accordance with the pressure difference between the high pressure fresh air and the low pressure gas. Therefore, in the illustrated arrangement, each of the reinforcement plates 17 has an extension 17a extending from the connecting portion 16a or 16b and overlapping the flexible plate 14 or 15, so that each of the extensions 17a resists the force acting on the connecting portion 16a or 16b. Further, since the above arrangement includes the holding ring 16 and the reinforcement plates 17 holding the flexible plates 14 and 15 therebetween, the connection can be provided by employing a seam resistance welding technique which can be performed with a higher speed and is suitable for a mass production. Generally, according to the seam resistance welding technique, the portion to be welded is held under pressure while it is molten so that the material therein is flown to reduce the effective thickness at the connection. However, in the aforementioned arrangement, the reinforcement plates 17 prevent the material of the flexible plates 14 and 15 from flowing as described above. Therefore, according to the above arrangement, the seam resistance welding technique can be employed to provide a connection of a sufficient strength.

It should further be noted that the present invention is not limited to the arrangement illustrated in the drawing but can be embodied in various ways. For example, since the pressure difference between the high temperature low pressure gas in the gas conduit d and the pressure of atmosphere outside the gas conduit 3, the seal between the gas conduit 4 and the rotary matrix regenerator 1 may not necessarily be identical to the sealing structure 2 for the air conduit 5 but may be constituted by a diaphragm of which resiliency is utilized to provide an effective seal. Further, the flexible plates 14 and 15 may be made of stainless steel or alloy steel, and belt or gear driving system may also be employed to transmit a power to the driving ring 3. The flexible plates 14 and 15 may not be straight in section but may be curved. The rotary matrix type regenerator 1 has been explained as being made of a ceramic material but it may be made of other heat resistant material of low thermal expansion such as stainless steel or heat resistant glass. The apertures in the rotary matrix type regenerator 1 may be of any shape provided that they can allow the fluids to be heat exchanged, that is, the combustion gas and the fresh air, therethrough. It should further be noted that the heat exchanger in accordance with the present invention can be used not only in a gas turbine engine but also in other internal combustion engines or boilers.

From the above descriptions, it will become clear that, according to the sealing arrangement of the present invention, the flexible plates 14 and 15 providing the spacing 18 can readily be formed by a stamp forming technique. The holding plate 16 can also be formed by a stamp forming technique or by bending. The arrangement in which the flexible plates 14 and 15 are secured at their outer peripheries with the holding ring 16 and at their inner peripheries with the flange 13 and the sealing member 12, respectively, is advantageous in that it is possible to use a resistance welding technique which is suitable for mass production for providing a connection efiective to resist a force tending to separate the flexible plates apart. Since the flexible plates 14 and 15 are disposed in parallel relation with each other, deformation due to the pressure difference can be substantially reduced, with the result that the fatigue life of the flexible plates can be increased. Further, since it is possible to provide the flexible plates 14 and 15 by stamp forming from flat plates, it is possible to eliminate any discrepancies such as buckling due to residuai stress created during their production as encountered in a conventional structure using an expansible bellows. The sealing structure in accordance with the present invention can provide a uniform and stable sealing force on the rotary matrix type regenerator l.

I claim:

1. A seal for a regenerative heat exchanger having a rotary matrix regenerator in which heat is exchanged between two gases passing through said regenerator and having different temperatures and different pressures, first conduit means for conveying high pressure gas, and a second conduit means for conveying a low pressure gas, said seal effecting a seal between said first conduit means and said rotary matrix regenerator with the aid of the pressure of the gas passing through said first conduit means, and comprising:

A. a pair of annular flat flexible plates disposed parallel with each other with a space therebetween;

B. a sealing member slidably contacting the surface of said regenerator for providing a sealing contact therewith, means for securing the outer surface of one of said flexible plates at its inner periphery to said sealing member and means for securing the other of said flexible plates at its inner periphery to the opening of said first conduit means faced to said regenerator;

C. an annular rigid holding ring of rectangular crosssection connected between said pair of flexible plates, and resistance welding means for securing said holding ring to the inner surface of the outer periphery of each of said pair of flexible plates; and

D. a pair of reinforcing plates secured to the outer surface of the outer periphery of each of said pair of flexible plates so as to resist the forces acting thereon.

2. A sea! as claimed in claim 1, which further effects sealing between said second conduit means and said rotary matrix regenerator with the aid of the pressure of the gas passing through said second conduit means, further comprising:

A. a second pair of annular flat flexible plates arranged in parallel with each other with a space therebetween;

B. a second sealing member slidably contacting the surface of said regenerator for providing a sealing contact therewith, means for securing the outer surface of one of said second pair of flexible plates at its inner periphery to said second sealing member and means for securing the other of said second pair of flexible plates at its inner periphery to the opening of said second conduit means faced to said regenerator;

C. a second annular rigid holding ring of rectangular cross-section connected between said second pair of flexible plates, and resistance welding means for securing said second holding ring to the inner surface of the outer periphery of each of said second pair of flexible plates; and

D. a second pair of reinforcing plates secured to the outer surface of the outer periphery of each of said second pair of flexible plates so as to resist the forces acting thereon. 

1. A seal for a regenerative heat exchanger having a rotary matrix regenerator in which heat is exchanged between two gases passing through said regenerator and having different temperatures and different pressures, first conduit means for conveying high pressure gas, and a second conduit means for conveying a low pressure gas, said seal effecting a seal between said first conduit means and said rotary matrix regenerator with the aid of the pressure of the gas passing through said first conduit means, and comprising: A. a pair of annular flat flexible plates disposed parallel with each other with a space therebetween; B. a sealing member slidably contacting the surface of said regenerator for providing a sealing contact therewith, means for securing the outer surface of one of said flexible plates at its inner periphery to said sealing member and means for securing the other of said flexible plates at its inner periphery to the opening of said first conduit means faced to said regenerator; C. an annular rigid holding ring of rectangular cross-section connected between said pair of flexible plates, and resistance welding means for securing said holding ring to the inner surface of the outer periphery of each of said pair of flexible plates; and D. a pair of reinforcing plates secured to the outer surface of the outer periphery of each of said pair of flexible plates so as to resist the forces acting thereon.
 2. A seal as claimed in claim 1, which further effects sealing between said second conduit means and said rotary matrix regenerator with the aid of the pressure of the gas passing through said second conduit means, further comprising: A. a second pair of annular flat flexible plates arranged in parallel with each other with a space therebetween; B. a second sealing member slidably contacting the surface of said regenerator for providing a sealing contact therewith, means for securing the outer surface of one of said second pair of flexible plates at its inner periphery to said second sealing member and means for securing the other of said second pair of flexible plates at its inner periphery to the opening of said second conduit means faced to said regenerator; C. a second annular rigid holding ring of rectangular cross-section connected between said second pair of flexible plates, and resistance welding means for securing said second holding ring to the inner surface of the outer periphery of each of said second pair of flexible plates; and D. a second paiR of reinforcing plates secured to the outer surface of the outer periphery of each of said second pair of flexible plates so as to resist the forces acting thereon. 